The moon phase display in a watch is a complication which, although old and very popular, often provides a very approximate display, generally designed for European users or users from regions close to the 45th parallel north. Moon phase displays for users from the southern hemisphere, where the appearance of the moon is reversed, are special and consequently more costly, and universal displays for both hemispheres are prohibitively expensive.
The phases of the moon appear differently in the northern and southern hemispheres or close to the equator.
Most moon display watches offer a display suitable for the temperate regions, but this display is not compatible with the appearance of the moon seen from the tropical or equatorial regions.
US Patent Application No. 2014/0247699A1 in the name of Sembritzki discloses a wearable device comprising a display device for displaying the phases of the moon. The image of the one or more moons is provided in the dial, and a rotating element is provided above the dial to provide images of a full, waning, new and waxing moon. The device provides for both bidirectional and unidirectional rotation of the rotating element. The device can simultaneously or selectively display moon phases consistent with views from the northern hemisphere and/or southern hemisphere.
U.S. Pat. No. 5,408,444 in the name of Kita discloses an electronic timepiece having a signal receiving function, the current time at the place where a user is located can be displayed without designating a regional name. The quasi-distance data between the satellites and the signal receiving point is calculated based upon the delay times of the signals transmitted by the satellites. The position data about the signal receiving point is obtained from four quasi-distance data. Subsequently, this position data is compared to the longitude/latitude data previously stored in ROM, to search for a city located nearest this signal receiving point. Furthermore, a judgement is made as to whether or not the current receiving point is coincident with the city located nearest the preceding receiving point. If these cities are coincident with each other, then the current time of the city stored in the time counting register is directly displayed. If no coincidence is established, the time counted by the time counting unit is corrected based upon the time difference data concerning the city located nearest to the current signal receiving point, and the corrected time is associated with the name of this city.
US Patent Application No 2010/0226213A1 in the name of Drugge discloses a timepiece or a wristwatch, which displays celestial ‘complications’ and meteorological events based upon calculations and conditions relevant to the geographic location of the timepiece. A memory storage device, a microprocessor, mechanical and software controlled graphical display systems and network connectivity facilitate the input of user selected complications, display options, geographic arguments and other variables. The timepiece is not limited to a preprogrammed geographic area or to predefined complications.